Year	% of land area
1990	39.66433566433567
1991	39.74039160839161
1992	39.81644755244755
1993	39.892503496503494
1994	39.968559440559446
1995	40.04461538461538
1996	40.12067132867133
1997	40.19672727272727
1998	40.27278321678322
1999	40.348839160839155
2000	40.32619462853157
2001	40.45264736658528
2002	40.579100104639
2003	40.70555284269271
2004	40.832005580746426
2005	40.95845831880014
2006	41.084911056853855
2007	41.21136379490757
2008	41.337816532961284
2009	41.464269271015
2010	41.59072200906871
2011	41.59072200906871
2012	41.59072200906871
2013	41.59072200906871
2014	41.59072200906871
2015	41.59072200906871
2016	41.59072200906871
2017	41.59072200906871
2018	41.59072200906871
2019	41.59072200906871
2020	41.59072200906871
2021	41.59072200906871